What is Power Factor?

The Power Factor (PF) of an AC electric power system is defined as the ratio of the real power flowing to the load to the apparent power, and is a dimensionless number between 0 and 1 (frequently expressed as a percentage, e.g. 0.5 PF = 50% PF). 

Real power is the capacity of the circuit for performing work in a particular time.  Apparent power is the product of the current and voltage of the circuit. 

Due to energy stored in the load and returned to the source, or due to a non-linear load that distorts the wave shape of the current drawn from the source, the apparent power will generally always be greater than the real power.

The significance of power factor lies in the fact that utility companies supply customers with volt-amperes, but bill them for kW. Power factors below 1.0 require a utility company to generate more than the minimum volt-amperes necessary to supply the real power. This increases generation and transmission costs for utility companies.

Companies should be improving their power factor for the following reasons:

• Although no yet commonplace, some utility companies are now charging commercial and industrial customers whose power factor is less than 0.95. These may appear on your bill as 'demand charge', 'reactive power charge', 'kVAr charge', 'use of systems charges' or 'availability charge'

• The maximum demand of a site is expressed in kVA - aggregation both real and reactive power. Reducing reactive power improves the power factor and reduces the maximum demand of a site'. This will lead to reduced kVA demand charges and increase capacity for future growth.
  

• If the system is carrying a high percentage of reactive power, voltage-drop will be excessive, impedences will be high and overall efficiency will be low. The strain on the electrical infrastructure is reduced if power factor is good.
  

        

E-Four Voltage Power Optimisation and Power Factor

 

One of the benefits of the E-Four Voltage Power Optimiser is the ability to improve power factor by addressing the fundamental inefficiencies of reactive loads rather than affecting the current/voltage waveforms.  The E-Four VPO delivers many of the same benefits as Power Factor Correction, but does not use capacitors, which are prone to failure and require regular maintenance.  Instead, it helps correct the underlying cause of poor power factor, while also saving energy (kWh).  Supplying a voltage closer to 220V rather than the raw grid voltage of around 242V results in significant reduction in the reactance of inductive loads.  In turn, this reduces levels of reactive power (kVAr) on the system.  As the real power (kWh) drawn by the site is also reduced due to reduced power dissipation in resistive components, the apparent power (kVA) is also substantially reduced.

 

The ability of E-Four Voltage Power Optimisation (VPO) technology to reduce energy (kWh) consumption on a site is well acknowledged, but the technology also provides a range of other benefits.  Accumulate, these create a more efficient, robust and reliable electrical supply for your site, and provide further financial benefits on top of the reduced energy costs.  All of the benefits are achieved through the installation of single solid state, self contained unit with no moving parts hence providing 100% security of supply for the site.

 

Power Factor Correction Systems

 

Power Factor Correction (PFC) systems operate by switching in or out banks of capacitors. 

Power factor correction brings the power factor of an AC power circuit closer to 1 by supplying reactive power of opposite sign, adding capacitors or inductors which act to cancel the inductive or capacitive effects of the load, respectively. For example, the inductive effect of motor loads may be offset by locally connected capacitors.  Unlike VPO, the use of capacitors and switching devices means it is essential that these units are maintained as these components can (and do) fail regularly.

 

A well designed PFC system will bring financial savings by reducing (or eliminating) the reactive power charges that you may be being charged by your utility provider. 

 

PFC will have minimal impact on the amount of energy (kWh) the site consumes and hence you will see little difference in the monthly/quarterly amount that is billed to you by your utility provider.